/*
	The MIT License

	Copyright (c) 2008 IFMO/GameDev Studio

	Permission is hereby granted, free of charge, to any person obtaining a copy
	of this software and associated documentation files (the "Software"), to deal
	in the Software without restriction, including without limitation the rights
	to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the Software is
	furnished to do so, subject to the following conditions:

	The above copyright notice and this permission notice shall be included in
	all copies or substantial portions of the Software.

	THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
	AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	THE SOFTWARE.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define PI 3.1415926536f

/* 
 * Paint a 2D texture with a moving red/green hatch pattern on a
 * strobing blue background.  Note that this kernel reads to and
 * writes from the texture, hence why this texture was not mapped
 * as WriteDiscard.
 */
__global__ void cuda_kernel_texture_2d(unsigned char* surface, int width, int height, size_t pitch, float t)
{
    int x = blockIdx.x*blockDim.x + threadIdx.x;
    int y = blockIdx.y*blockDim.y + threadIdx.y;
    float* pixel;
       
    // in the case where, due to quantization into grids, we have
    // more threads than pixels, skip the threads which don't 
    // correspond to valid pixels
	if (x >= width || y >= height) return;
	
    // get a pointer to the pixel at (x,y)
    pixel = (float*)(surface + y*pitch) + 4*x;

	// populate it
	float value_x = 0.5f + 0.5f*cos(t + 10.0f*( (2.0f*x)/width  - 1.0f ) );
	float value_y = 0.5f + 0.5f*cos(t + 10.0f*( (2.0f*y)/height - 1.0f ) );
	pixel[0] = 0.5*pixel[0] + 0.5*pow(value_x, 3.0f); // red
	pixel[1] = 0.5*pixel[1] + 0.5*pow(value_y, 3.0f); // green
	pixel[2] = 0.5f + 0.5f*cos(t); // blue
	pixel[3] = 1; // alpha
}


extern "C" 
void cuda_texture_2d(void* surface, int width, int height, size_t pitch, float t)
{
    cudaError_t error = cudaSuccess;

    dim3 Db = dim3( 16, 16 ); // block dimensions are fixed to be 256 threads
    dim3 Dg = dim3( (width+Db.x-1)/Db.x, (height+Db.y-1)/Db.y );

    cuda_kernel_texture_2d<<<Dg,Db>>>( (unsigned char*)surface, width, height, pitch, t );

    error = cudaGetLastError();
    if (error != cudaSuccess) {
        printf("cuda_kernel_texture_2d() failed to launch error = %d\n", error);
    }
}




